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→Acid and Base:
==== Acid and Base: ====
==== Acid and Base: ====
Special type of substances are used to test whether a substance is acidic or basic. These substances are known as indicators. The indicators change their colour when added to a solution containing an acidic or a basic substance. Turmeric, litmus, China rose petals (Gudhal), etc., are some of the naturally occurring indicators.
The word acid comes from the Latin word acere which means sour. Acids are sour in taste and change the colour of blue litmus to red. Curd, lemon juice, orange juice and vinegar taste sour.
Whereas, bases are bitter and change the colour of the red litmus to blue.
==== Process: ====
==== Process: ====
Litmus paper as indicator:
'''Litmus paper as indicator:'''
When litmus paper added to an acidic solution, it turns red and when added to a basic solution, it turns blue. It is available in the form of a solution, or in the form of strips of paper, known as litmus paper. Generally, it is available as red and blue litmus paper.
Step 1: Mix some water with lemon juice in a plastic cup/tumbler/test tube.
Step 2: Put a drop of the above solution on a strip of the red litmus paper with the help of a dropper.
'''Is there any change in colour?'''
Step3: Repeat the same exercise with the blue litmus paper.
Step 4: Note down if there is any change in colour.
Step 5: Perform the same activity with the following substances: Tap water, detergent solution, aerated drink, soap solution, shampoo, common salt solution, sugar solution, vinegar, baking soda solution, milk of magnesia washing soda solution, lime water.
Step 6: Record your observations the in Table
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